When a mid-sized software firm announced that its four-day workweek trial had 'proven' the shorter schedule boosts productivity, the claim traveled quickly. The company reported that total output over the six-month trial matched the output of the preceding six months, even though employees worked one fewer day each week. If the same work was done in less time, the reasoning went, workers must have grown more productive per hour. The inference is tempting but incomplete. The trial coincided with the launch of a new project-management system that automated tasks previously done by hand, and with the departure of two underperforming teams whose projects were quietly shelved. Output per remaining worker might have risen for reasons having nothing to do with the compressed schedule. Moreover, the comparison period—the preceding six months—included a stretch of seasonal slowdown, so the baseline against which the trial was judged may have been unusually low. None of this proves the four-day week failed; employees reported feeling less exhausted, which carries its own value. But to credit the schedule alone with steady output, while ignoring the tools, the staffing changes, and the uneven baseline, is to award a prize before the race has been fairly run.